I am more than happy to assist you with your picture messaging on your device. May I ask are you able to access the Internet on your device? If not then please reply with the error message that you get. Also, I have some other questions to get a clear understanding of the issue. They are as follows:
Once you have provided the answers to the questions above then I can determine if it is network or device related. If you believe that the issue is device related then I would recommend doing a factory reset on the device. As always, I encourage that you back up your contacts using backup assistant prior to performing the factory reset. I have also posted the reset steps below.
From the main screen, press Contacts [Right SoftKey].
PressOptions [Right SoftKey]
Select Manage contacts
Scroll to Erase ALL Contacts, press OK.
Erase All Contacts displays.
Scroll to Yes or No, press OK.
Enter Lock Code displays.
Enter the 4 digit lock code ( default: last 4 digits of phone number ).
Once the device has been resetted back to factory settings, you may have to reactivate your service. This can be done by calling *228 and selecting option 1 when the automated response plays. After the activation process, please test your voice services and your text & picture messages. If the problem still persists then please reply to this message with your findings.